1. Field of the Invention
The present invention relates to a control valve for controlling the flow of working fluid.
2. Description of the Related Art
An automotive air conditioner is generally configured such that it includes a compressor, a condenser, an evaporator, and so forth arranged in a refrigerant circulation passage. Various types of control valves are provided (see Reference (1) in the following Related Art List, for instance). Here, these various types of control valves are, for example, used to switch the refrigerant circulation passages according to the operation state in such a refrigeration cycle and regulate the flow rate of refrigerant. A mechanical valve, which opens and closes a valve section through a balance between the force exerted by a pressure received from the refrigerant and the biasing force of a spring opposing the force exerted thereby, and an electrically driven valve, provided with an actuator for electrically regulating the opening degree of the valve section from the outside, are used, as appropriate, as the control valves used herein.
Related Art List
(1) Japanese Unexamined Patent Application Publication (Kokai) No. Hei11-287354.
In such an air conditioner as one described above, there are cases where the discharged refrigerant contains foreign material, such as metallic powders, as a result of frictional wear and the like of a sliding portion of the compressor. The foreign material may flow into the sliding portion of the control valve in a process where the refrigerant circulates in the refrigeration cycle and may hinder the smooth sliding operation. In other words, pressure differences between an upstream side and a downstream side of the valve section occur in a valve element. Thus, a pressure difference also occurs in between an inlet port and an outlet port of the sliding portion of the valve element, and the foreign material flows into the sliding portion through this pressure difference. As a result of adhesion of the foreign material to the sliding portion may possibly interfere with the smooth opening and closing of the valve element. The same problem may arise not only in vehicles but also in apparatuses provided with the control valves.